IEEE Spectrum July, 2008 - 27

He began Googling, looking for projects involving mobile robots, and became
fascinated with videos of RoboCup, the
international robotic soccer championship. One day in the fall of 2003, he mentioned the videos to another MIT friend,
Marjolein C.H. van der Meulen, now a
professor of mechanical and aerospace
engineering at Cornell, who promptly
said, "You have to meet this RoboCup
guy at Cornell!" The colleague in question
was Raffaello D'Andrea, who had led the
Cornell team to no less than four RoboCup world championships.
That year, D'Andrea had just begun a
sabbatical at MIT, and Mountz arranged
to meet him for half an hour on campus.
They talked for three hours. They met the
next day, and again the following weekend. D'Andrea was hooked. "Mine was
probably the shortest-lived sabbatical of
all time," he quips.
In late 2003, Wurman and D'Andrea
officially joined Distrobot. The company
set up shop in a small warehouse in Burlington, Mass., not far from iRobot. In
fact, they had chosen the Boston area
because of the robotics expertise found
there. The warehouse was just a big
empty space, which they heated as little
as possible to keep costs down. "It was
so cold we kept our drinks in a little side
room," D'Andrea recalls.
The founders hired two engineers and
one computer scientist and got to work.
The first weeks consisted mostly of brainstorming. Progress was slow. One day,
Mountz gathered everybody and said,
"Stop doing stuff on the whiteboard. You
guys should do less thinking and more
coding." He wanted to see something actually doing something.
D'Andrea and Wurman, on the other
hand, were wary of a rushed design
that could lead to problems in the long
term. "From this tension we arrived at
an engineering philosophy that lasts to
this day," Wurman says. "We do rapid
prototyping and demonstrations, and
then a cycle of deep thinking and major improvements."
To build the first prototypes, Mountz
hired some of his MIT fraternity brothers
who worked in robotics. The initial
models were metal boxes on wheels, the
kind used in motorized wheelchairs. They
had no navigation system and no collisiondetection capability. The machines could
move only from one point to another and
often sent boxes flying off racks.
D'Andrea and his team set out to redesign the robots entirely. They modified
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the rack-lifting mechanism, optimized
the wireless module, added safety and
power-management features, and most
important, came up with a totally new
navigation and control system.
Their innovation was to put bar-code
stickers on the floor and equip the robots with cameras to read them. As the
robots move, they read the encoded information to learn their coordinates in
the warehouse. At the same time, the robots' control systems determine how far
off their bodies are from the center of the

stickers. If, for instance, a robot is a bit off
to the right, the control system nudges it
to the left.
The control system also reports its
readings to the computer cluster to share
that information with other robots. This
distributed-control approach improves
their navigation capabilities. Say a robot
sees certain stickers off to the left. Instead
of simply correcting its course by turning
to the right, the robot first checks what
other robots see-what the "wisdom of
the crowd" is. If most of them see cen-

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Table of Contents for the Digital Edition of IEEE Spectrum July, 2008